Open the Messages app
Find the conversation or message you want to erase
Swipe left on the conversation and tap Delete
Or open the conversation, press and hold the message, then tap More
Select the messages you want to delete
Tap the trash icon
Tap Delete Message or Delete All
To delete multiple conversations, tap Edit in Messages
Tap Select Messages
Choose the conversations
Tap Delete
Confirm deletion
To erase all messages from a conversation, open it, tap the contact name or number, then tap Info
Tap Delete Conversation if available
To automatically delete old messages, go to Settings
Tap Apps or Messages
Tap Keep Messages
Choose 30 Days or 1 Year
To erase messages from iCloud, turn off Messages in iCloud and delete the messages on all devices
To permanently remove recently deleted messages, check the Recently Deleted section if available and delete them there